Dissimilar Metal Joining With Ni Plating for Corrosion Resistance
Solution Overview
Problem
Dissimilar metal joined materials face challenges with corrosion resistance, as existing passive films are brittle and prone to cracking, affecting their longevity and performance characteristics like curvature coefficient and volume resistivity.
Innovation Solution
A dissimilar metal joined material comprising a high thermal expansion layer and a low thermal expansion layer, with a Ni plating layer of 10 nm to 120 nm thickness applied to the high thermal expansion layer for enhanced corrosion resistance, maintaining the material's original characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passive film is formed on the surface of the dissimilar metal joined material to improve corrosion resistance, then corrosion resistance is improved, but the film cracks when the material repeats curving, making it difficult to maintain corrosion resistance for a long period
Solution Approach 1:
The invention changes the physical and chemical parameters of the protective layer by forming a metallic plating layer with specific thickness (1 nm to 100 nm) and specific composition (containing Ni and Cu) instead of using a conventional passive film. This metallic plating layer has different mechanical properties that allow it to withstand curving without cracking while maintaining corrosion resistance.
Solution Approach 2:
The invention creates a composite structure consisting of the dissimilar metal joined material (bimetal or trimetal) combined with a metallic plating layer. This composite structure integrates the corrosion resistance function with the flexibility needed to accommodate curving, as the plating layer contains multiple elements (Ni, Cu) that provide both protective and ductile characteristics.
2Reliability
If the thickness of the passive film is increased to improve corrosion resistance, then corrosion resistance is improved, but the film easily cracks further, affecting characteristics such as curvature coefficient and volume resistivity
Solution Approach 1:
The invention optimizes the thickness parameter of the protective layer to a specific range (1 nm to 100 nm) and changes its compositional parameters (containing Ni and Cu). This parameter optimization ensures the layer is thick enough to provide corrosion resistance but thin and flexible enough to accommodate curving without cracking, thus maintaining the curvature coefficient.
3Reliability
If a corrosion resistant plating layer is provided on the high thermal expansion layer, then corrosion resistance is improved, but the plating layer may affect the original characteristics of the material
Solution Approach 1:
The invention applies a plating layer with partial coverage (1 nm to 100 nm thickness) rather than a thick complete coating. This partial action provides sufficient corrosion protection while minimizing the impact on the original material characteristics such as thermal expansion properties and electrical conductivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The Ni plating layer provides effective corrosion resistance, prolonging the material's life and minimizing changes in curvature coefficient and volume resistivity, while being flexible enough to withstand temperature changes without cracking.
Implementation Method 1
plating at least the surface of the high thermal expansion layer with a Ni plating solution to form a corrosion resistant plating layer
Implementation Method 2
a degree of curvature changes with a temperature change
Data Source
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Figure 5~6
AI summary
An object of the present invention is to provide a dissimilar metal joined material that has corrosion resistance that can prolong life resulting from corrosion and has a small difference from original characteristics. There is provided a dissimilar metal joined material including: a clad material including a high thermal expansion layer composed of an alloy containing Mn, and a low thermal expansion layer composed of an alloy containing Ni, the low thermal expansion layer being joined directly to the high thermal expansion layer or via an intermediate layer; and a corrosion resistant plating layer provided on at least a surface of the high thermal expansion layer, the corrosion resistant plating layer having a thickness of 10 nm to 120 nm.